研究目的
To prepare thermodynamically stable tungsten (W) nanopyramids by coating a W needle with a collodion containing powdered palladium oxide and annealing it under ultrahigh vacuum to adsorb palladium (Pd) atoms onto the apex of the W needle.
研究成果
A W nanopyramid coated with a Pd film was fabricated using a collodion containing powdered PdO as the Pd source. The nanopyramid with three {211} faces was observed, but it did not achieve a single-atom tip. Further considerations are required to yield any findings about conditions required to grow single-atom tips.
研究不足
The nanopyramid did not achieve a single-atom tip, and the annealing temperature may have been insufficient for completely reducing PdO. Impurities such as carbon or oxygen might have hindered the accurate growth and completion of the nanopyramid.
1：Experimental Design and Method Selection:
The study involves coating a W needle with a collodion containing powdered PdO, annealing it under ultrahigh vacuum, and observing the atomic structure via field ion microscopy (FIM).
2：Sample Selection and Data Sources:
A 0.1-mm-diameter, 4-mm-long polycrystalline tungsten wire was used, sharpened by electrochemical etching in 2-M aqueous KOH.
3：1-mm-diameter, 4-mm-long polycrystalline tungsten wire was used, sharpened by electrochemical etching in 2-M aqueous KOH.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Ultrahigh-vacuum (UHV) chamber, optical pyrometer, field ion microscopy (FIM) setup, He or Ne as the imaging gas.
4：Experimental Procedures and Operational Workflow:
The W wire was sharpened, coated with PdO-containing collodion, annealed in UHV, and observed via FIM at about 100 K.
5：Data Analysis Methods:
The atomic structure of the W tips was analyzed using FIM images to study the formation of nanopyramids.
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